180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150
180 - ( 10 + 20 )
= 180 - 30
= 150